Diff between Thread and Runnable

To implement threads, you can use both Thread class or a class that implements Runnable interface as follows :

class MyThread extends Thread {

    public void run() {

        …

    }

}

or

class MyRunnable implements Runnable {

    public void run() {

        …

    }

}

MyRunnable r = new MyRunnable() ;

Thread t = new Thread(r);

In an Object oriented aspect, the second method is more preferrable, because you extend a class when you want to make it different from it’s superclass, and change it’s behaviour(s) . But when you extend Thread class for use as a thread generally you do not make a change on thread object’s behaviours. So you want to extend Thread when you really change the class Thread. And if you extend Thread class, you cannot extend another class, so using Runnable interface gives you the ability of extending another class. And (as far as I know) these two methods cause no performance difference when you prefer one for another.